Ever drive by a bicycler on a 50MPH road who wouldn't get out of your way and...?

Sounds like assault with a deadly weapon and reckless driving if you ask me. One could even make a pretty good case for attempted murder or murder if you actually kill them.

Is the trivial inconvenience of moving over to pass a bicyclist so horrible that it justifies killing someone? Could you throw a hissyfit over something more trivial than having to move over to pass a bicyclist?

By law, bicyclists have as much right to use the road as you do. Operating a motor vehicle does not make you more important than them and it does not give you priority over them. You do not own the road. By law, you have to share the road with bicyclists.

In most jurisdictions, motorists are required by law to maintain a safe distance when passing bicyclists. In most jurisdictions, it is illegal to use your horn to harass anyone or for any purpose other than to ensure safe operation. I'm guessing that you either honked or passed close or both. Why would you be surprised that someone would cop an attitude when you just harassed and/or threatened and/or intentionally endangered them?

You need to let go of your childish delusions of entitlement. You need to take a driver's education class because it's clear that you do not know how to drive. You need to seek help from a psychologist because you are psychotic.